There has been suggested an air bag device wherein, at the time of a collision of an automobile, the magnitude of the shock will be detected and, if the shock is more than will injur the riders, a gas generator will be operated. The air bag will then be filled with gas, and will be inflated to cushion the shock to the riders in the automobile.
With such conventional air bag device, in detecting and transmitting the shock at the time of a collision and starting the operation of filling the air bag with the gas of a gas generator, generally the magnitude of the shock is electrically detected. The electric detecting signal is sent to a detonation priming device for starting the gas generator, the detonation priming device is ignited to operate the gas generator, and the air bag is filled with the gas so as to be inflated.
Such conventional means requires an electric detecting device, transmitting system, igniting device and detonation priming device. Therefore, the electric structure for protecting the current source and wiring at the time of a collision must necessarily be complicated. Accordingly, such a starting system for an air bag device is so high in cost that the air bag device itself is high in cost.